Steps to reproduce the issue

I am not native English, but:
When I look at all the labels I think that callback must be written with a capital 'C' in these srings:
PLG_RECAPTCHA_EXPIRED_CALLBACK_LABEL="Expired callback"
PLG_RECAPTCHA_ERROR_CALLBACK_LABEL="Error callback"
PLG_RECAPTCHA_INVISIBLE_EXPIRED_CALLBACK_LABEL="Expired callback"
PLG_RECAPTCHA_INVISIBLE_ERROR_CALLBACK_LABEL="Error callback"

Expected result

PLG_RECAPTCHA_EXPIRED_CALLBACK_LABEL="Expired Callback"
PLG_RECAPTCHA_ERROR_CALLBACK_LABEL="Error Callback"
PLG_RECAPTCHA_INVISIBLE_EXPIRED_CALLBACK_LABEL="Expired Callback"
PLG_RECAPTCHA_INVISIBLE_ERROR_CALLBACK_LABEL="Error Callback"

Actual result

System information (as much as possible)

Additional comments